


Lucky Hearts

by ShamanicShaymin



Category: Undertale (Video Game)
Genre: Awkward Sexual Situations, First Time, Heart Sex (Undertale), M/M, Mettaton's idea of human genitalia, No Skeleton Ghost Penis, Papyrus using his dating book for sex advice, Plot What Plot/Porn Without Plot, Robot Sex, Sensitive bones, Soul Sex, Spanking, Underwear
Language: English
Status: Completed
Published: 2015-12-20
Updated: 2015-12-20
Packaged: 2018-05-07 21:25:36
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,939
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5471309
Author URL: https://archiveofourown.org/users/ShamanicShaymin/pseuds/ShamanicShaymin
Summary: <blockquote class="userstuff">
              <p>Today's play-date with Mettaton went perfectly, and it was all because the Great Papyrus chose to wear his lucky underwear.</p>
            </blockquote>





	Lucky Hearts

**Author's Note:**

  * For [mangle_loves_slash](https://archiveofourown.org/users/mangle_loves_slash/gifts).



> Smut starring an 80s glam bot and a precious cinnamon roll. :)

Today's play-date with Mettaton went perfectly, and it was all because the Great Papyrus chose to wear his lucky underwear. The skeleton believed they unlocked all of his life's successes: He wore them when he found the action figure that got stolen by the annoying dog (left behind in Sans' dirty sock pile). Not to mention he had them on when he stayed up until dawn at Undyne's house until she finally decided to train him. Though he hadn't equipped the lucky underwear on the day the human arrived, he was certain wearing it three days prior influenced future events, such as the liberation of monsterkind. So they _must_ work.

Even now, while Papyrus donned his favorite pajamas—pink cotton with meatball-red polka dots—the lucky underpants stayed on. Mettaton laid his head on the skeleton's lap as they watched _Mettaton: The Movie IX_ from the old flat-screen television. Papyrus smiled, stroking the robot's raven hair as he gazed back and forth between the sexy calculator on the screen and the handsome celebrity sharing the couch with him. The robot sighed in contentment, his heart-shaped lips as rich and pink as the rose petals showering his rectangular body in the movie. The skeleton blushed, wondering what it'd be like to have lips of his own so he could kiss them.  
  
“Mettaton?” The ex-sentry's throat tightened. Seconds of silence rolled down his spine as he contemplated whether or not this was a good idea. He willed himself not to shiver; the Great Papyrus never gets nervous!  
“What is it, darling?” That voice. God, that voice. In the early days, long before he met Mettaton in person, Sans happened to fall asleep with the television on. Papyrus was about to switch it off when he saw that MTT was on. Wondering what the fuss was about, the skeleton watched the entire thing, then cursed himself when he realized how late he stayed up. But when he went to bed that night, he couldn't stop thinking about how the rectangle sounded, and how relaxing it was to listen to him speak. Naturally, Papyrus saved up enough gold to buy MTT music over the Internet, and when Mettaton announced the release of “Mettaton Reads The Dictionary: Volumes 1-26,” Papyrus was the first to pre-order. His favorite entries, of course, were “skeleton”, “spaghetti,” “puzzle,” and “papyrus.” Who imagined Mettaton can now speak these words to him _in person_ any time he pleased?  
“I've been contemplating our relationship! We've been together for a long time, haven't we?”  
“Indeed.” Mettaton sounded pleased, as though he was the luckiest robot alive. How could someone make the Great Papyrus feel so humble?  
“So, Mettaton. You are free to take me up on this offer I'm about to give you! You don't have to take it; after all, what I'm about to bestow is rather daunting. For you, I mean! Though I guess me too... anyway, you must be wondering what that offer is! I want to—well—how do I put this...?”  
“Yes Pap?”  
“I think we should have sex!” Papyrus announced. His cheekbones flushed red and it only got worse as he continued talking, “According to this dating manual I got from the library, it's one of many ways that couples show their affection! It is particularly intimate, so I can see why you might be intimidated. I don't wish to pressure you into something you're not ready for. But rest assured, if you're interested in 'hitting the sack', 'stemming the rose,' 'breaking the maidenhead'—what does that mean?—or if you simply want to 'make love,' I, the Great Papyrus, shall cater to your every need and desire! For I am an expert in all manners of love, including all things erotic! Just tell me what you want, and I'll do my best to please you!”  
“P-Papyrus!” Mettaton spluttered, immediately sitting up. The robot stared at him in shock, his own cheeks as pink as his boots. He composed himself by taking a deep breath, like he was on live before his audience. “Darling, do you know what you're getting yourself into?”  
“I, uh... of course I do! Into you, as they say! Nyeh heh heh!” Papyrus internally recoiled, and beads of sweat collected on his skull. “Or, you know, we can forget I ever said anything! The Great Papyrus has had enough excitement for one night!”  
“Sweetheart, it's not that! It's just that you seem so—!” While he had the word at the tip of his tongue, a different thought struck him. Mettaton chuckled, and his pink lips curved into a wicked smirk. “You naughty, naughty skeleton. What have you been hiding from me all this time? How many ways were you planning to ravish my luscious body?”  
“I-I—Well, actually... you still want to try?” A metaphorical weight dropped from Papyrus' shoulders. This could've been so awkward! He stiffened when the robot cupped his hand around his cheekbone.  
“Show me your fantasies, darling. I'll make them come true.”  
  
Papyrus stammered, but when Mettaton pressed his mouth to his teeth, his worries melted away like snow under the sun. The robot proceeded to kiss his way up, and his hands weaved over his partner's skull like the finest statue ever sculpted. Coated in his finest MTT-brand lipstick, his lips marked Papyrus' cranium like a shower of hearts. The skeleton returned the kiss in the best way he knew how, nibbling the robot's bottom lip and tasting raspberries from the not-yet-dry lipstick. Mettaton moaned and reached out with his tongue, sending shivers down the skeleton's spine. Nervous but curious and excited, Papyrus wrapped his arms around Mettaton. The celebrity settled into his partner's lap, and the ex-sentry's cheekbones heated up as those long shapely legs hooked around him.

“So, uh... that's the first step taken care of!” Papyrus gasped when they parted for breath. “Next, we should be engaging in something called 'foreplay!'”  
“Isn't that what we're doing now?”  
“That's true! Mettaton, you're already so good at this! You might even be better than the Great Papyrus!”  
“We've hardly even started.” Mettaton giggled. “But thank you, Pap. I'm flattered.”  
“Actually, there's something you could do for me, if you don't mind.” Contemplative, the skeleton stared at the leg stretching out beside his shoulder blade, its pink boot sharp and assertive. “Do you think I could... touch your legs? I've always wondered what they felt like, but I'd always been too shy—wait, that is not right! The Great Papyrus never gets shy! I just... think it would've been too impolite to ask, that's all. I do admire them!”  
“Of course you can! Touch wherever you like.” With that, Mettaton withdrawn from Papyrus and lay back on the couch, spreading himself like he did in all his movies. Coquettishly, the robot trailed his fingers from his thighs to his voluptuous hips, before briefly toying with the belt that contained his heart. He purred as he fondled the dial on his chest before finally weaving his hand through his hair, his seductive pink eyes half-lidded with sin. “I'm all yours, gorgeous.”  
“W-Wowie...!” Redder than all the flames of Hotland, Papyrus hesitated as he gazed up and down Mettaton's body. His bony hands trembled before finally stroking one of the robot's calves, cradling it like something precious and delicate. The black spandex was soft, supple, and strong, and Papyrus wanted more of it. Growing bolder, the skeleton worked his way up, squeezing and massaging those smooth thighs. Is this what having flesh is like? He watched Mettaton for signs of discomfort, but the robot hummed in absolute bliss.

Carefully, the skeleton slid off Mettaton's boots, setting them aside where nothing could dare tarnish them. The spandex stretched down the rest of his legs as well, seamless as the wings of a black swan. The skeleton held one of the robot's feet, his bony fingers caressing the ankle. He lifted it against his cheek, and gasped from how cool it felt against bare bone. With slow consideration, he nipped one toe at a time, eliciting giggles from the robot. He repeated the process with the other foot before smiling and nuzzling against its sole.  
  
"Mettaton! Your feet are so soft!" The skeleton laughed lightly.  
"Would you like to feel something softer?" Mettaton pulled his foot away, sitting up so he can take Papyrus' hands into his own. The skeleton's eyes nearly bulged out of his skull when the robot guided his hands on the cheeks of his backside. Papyrus squeezed impulsively, and Mettaton backed into his touch with joy, coaxing him for more. If it's possible to die from embarrassment, Papyrus would be a pile of dust by now. But wowie, if this wasn't the best way to die! Touching Mettaton in a place where he never imagined he could touch... and the robot celebrity is right, it _is_ soft! Yet so tough... he wondered if he could squeeze any harder, he might meet the metal exoskeleton that made up who Mettaton is.  
  
“Hit me, darling~” Mettaton purred. “Hit my ass hard...”  
The skeleton froze. If there's one thing the dating book advised, it's to _never, ever hit your partner._ Not that Papyrus planned on it; the idea of abusing anyone made him ill. Yet Mettaton asked him to do it and he promised to please him. Not to mention the book itself said he should listen to his partner. What should he do?  
“I-I don't think this is a good idea!” Papyrus blurted, sweating. “I don't want to hurt you, Mettaton!”  
“It's all right, dear! Just do it.”  
“But... but the book says it's wrong!”  
“Don't mind what the book says. Do _you_ want to do it?”

_What a weird question. Of course I don't! Right?_

“Are you sure you want me to do this?” Papyrus asked. “If it's what you want, I suppose it'll be all right...”  
“Only if you're comfortable, dear.” Mettaton assured, brushing the skeleton's cheekbone. “You're such a kind skeleton, and I know you won't mean me any harm. I know you'll take good care of me when it's over, darling. But if you're still worried, there's plenty of other things we can do.” Mettaton smirked. “Plenty.”  
“...Okay then! If you say so, Mettaton. Now turn around!”  
Mettaton obeyed, on his knees so Papyrus could admire the view. “Like this?”  
“Perfect! Now hold still! I want to be sure I get this right!”  
  
_Smack!_ The robot cried out from the impact, and the skeleton looked back and forth between him and his hand.  
  
“Are you okay?” Papyrus asked. “Am I hurting you?”  
“Do it again! More!”  
“O-Okay! Just tell me if you want me to stop!”

_Smack! Smack!_ With each hit, the robot screamed and moaned. Mettaton squirmed with every blow the skeleton delivered, and he begged harder, harder...! Soon Mettaton was a mess, his eyes watering and his tongue hanging out. His speakers vocalized his pleasure when his mouth couldn't formulate the words himself, garbled with cheers and doting affection for the skeleton. He stopped when he saw Papyrus holding his hand, and he turned around to see what was the matter.

“My sweet skeleton, are you okay?”  
“Oh I'm fine! But...” Papyrus rubbed at his wrist. “Do you mind if we stopped for now? My hand hurts.”  
“Of course, dear.” Mettaton took the skeleton's hand into his own, kissing it better. “You did such a good job...”  
“That was actually kind of fun!” Papyrus grinned. “Maybe the book is wrong after all! I had no idea some monsters like being hit!”  
“You'd be quite surprised.” Mettaton giggled.  
“Hey, I know! What if _I_ like being hit? Though... I don't know if I'm ready for that.” Papyrus shuffled nervously. “I kind of just want to make love, and not much more than that...”  
“There's no need to rush yourself, honey. We'll do whatever you like.” Mettaton soothed, before leaning in to kiss him. “Speaking of which... how do you want me to repay you?”  
“...Could you hold me, Mettaton? I just want to be hugged... and kissed...”  
“Would you like me to take off those cute pajamas of yours? May I touch your ribs and find which of your bones are the most sensitive? Do you want me to run my hands along your sternum?”  
“Yes! Yes! Please, Mettaton!”

His idol proceeded to unbutton the skeleton's top, then when he was done, he dropped them on top of his boots. His hands massaged Papyrus' clavicles, bidding him to relax. His lips touched his sternum, and he dragged his tongue to the top where it met with the vertebrae of the skeleton's neck. Papyrus groaned as the robot coated his neck with loving strokes of his tongue before sucking tenderly. His hands fondled Papyrus' ribs everywhere, and the skeleton's breathing staggered. Papyrus embraced Mettaton, partly for support and mostly for intimacy.

“Mettaton?” Papyrus gasped. “Before we go any further, I want to show you my greatest secret!”  
“What is it, darling?”  
“All this time, I've carried something that allowed our dates to go so well! You'll be the first person to know about this aside from my brother... you've earned that privilege! Now I'll show you the truth!”

With dramatic resolve he hoped worthy of an MTT episode, the skeleton tore down his pajama bottoms and tossed them aside with flair. His lucky underwear flashed under the spotlight, exposed in all its brilliant glory. The boxers embodied a rich orange color, the spirit of bravery itself. Printed on the sun-colored cloth were white rockets with aqua-tinted wings blasting off in different directions.

“This is my lucky underwear!” Papyrus declared, beaming with pride. “Have you ever wondered what makes the Great Papyrus so great? Have you wondered how I got to be so strong? So smart? Where I get my inspiration for puzzles? What the secret ingredient is to my spaghetti recipe? _It's all in the power of this underwear!_ I thought it would be important to wear on all our dates! After all, what kind of boyfriend would I be if I don't give you the best of the best? You said on your show that clothes make the monster. So, in a way... you're actually responsible for my success!” Papyrus raised his hands to his face, his eyes wide with revelation. “My god, Mettaton... you've been my lucky underwear all along! It must be fate!”  
“Oh sweetie...!” The robot celebrity blushed a deep rose, gazing in awe at the powerful garment. “All this... for me?”  
“Since I'd been planning to ask you if you wanted to—erm—'do the deed' with me, I figured this would be the most lucky-underwear situation of all lucky-underwear situations! By the time we take off our clothes, my lucky underwear will—will—oh my gosh...” Sweat gathered on his skull, and the ex-sentry grew apprehensive. “Nyeh heh... It completely slipped my mind! Underwear—lucky and unlucky and everything in between—counts as clothing! I'll be stark naked! The gifts bestowed upon me will be gone!”  
“You can still keep your underwear on if you—”  
“No! I mustn't! If we're going to do it, we must go all the way!” The skeleton turned scarlet and smiled guiltily. “I'm sorry, Mettaton. I really wanted to make this night special, but I should've thought things through! I got so excited about the prospect of making love to you for the first time, and... and without my lucky underwear, I fear this all might fall apart!”  
“Pap, you mustn't worry so much. You'll do fine.” Mettaton took Papyrus' hands into his own, his expression soft. “If it makes you feel better, I... I'm new to this myself.”  
“You are? But you seem so confident!”  
“Yes indeed!” Mettaton chuckled. “In all seriousness though, running a family-friendly show and having such a tight schedule, I haven't had the time to really... 'explore' my new body, like I should. Then we started dating, and I thought about this 'sex' thing. I think about you all the time, darling, and I think about how much I want to share my body with you. It was my dream, being corporeal... to experience sensations like this. But since you never brought up anything of the sort, I assumed you weren't interested. I'd been a little intimidated to ask, since you seemed so happy with me... I didn't want to lose that. I didn't want you to feel... used. So, when you asked to make love to me, it caught me quite off-guard! Whatever happens, don't worry about disappointing me. You are my lucky star, Papyrus. With you in my life, you make every waking moment absolutely beautiful!”  
“Mettaton, I... I love you so much!” Papyrus cried. The skeleton wriggled out of his prized boxers, letting them slide to the floor. “Now that I know we're both virgins, I, the Great Papyrus, shall strive harder than ever to please you! Lucky underwear or no lucky underwear, our first time is going to be fantastic! I'll make certain of it!”  
“Then it's time I show you my latest upgrade. Get ready, gorgeous!”

Mettaton shifted his belt and rolled down the black spandex pants he'd been wearing up to this point. Papyrus' eyes bulged at the sight of the robot's legs; like Mettaton's arms, they were long and plated with metal sleek as silver scales. After tapping a series of buttons hidden beneath his heart, one of the plates shifted to form an opening on Mettaton's crotch. Rising in place was a tall cone slathered in glitter twinkling silver, blue and bronze. The tip of the cone glowed as bright as Waterfall's gems, casting shadows on Mettaton and Papyrus while rotating light patterns on the ceiling like a disco ball. Papyrus squinted, blinded by the intensity of his idol's tool.  
  
“This...” Mettaton announced, stroking the cone like a pet. “...I'm proud of this. I've talked with Dr. Alphys and did some research, and according to her animes and mangas, human genitals look fabulous! They're made up of strange sparkles that shift color, which I do believe is called... 'mosaic.' Sometimes people have these cones that light up when they're aroused, which isn't quite as common in cartoons, though there's plenty of them in comics. Of course, when Alphys made mine, I asked for some small adjustments, so it's not wholly accurate to human anatomy. But I couldn't bear to have any of those nasty black bars like some humans wear! It's so unsightly! They shouldn't cover themselves up when they've got such lovely glitter as part of their bodies... if you're going to strut your stuff, you should let _all_ of yourself shine!”  
“Wowie! It's—It's beautiful!” Once his eyes adjusted to the brightness, Papyrus couldn't tear his eyes off that gorgeous, glittering cone. Tentatively, he reached out to touch it, marveling at its majesty. Hot and somewhat sticky, the cone twitched in reaction, sparking to life in his hand.  
“Mmm... Papy...”  
“Now is the time we do the third and final step! Intercourse!” Papyrus announced. “Though... I seem to recall that skeletons never possessed cones of light or anything similar. This might be a problem!”  
“Leave it to me, darling. I think I know just what we need to do...” The robot smirked. “Would you mind lying back for me?”  
  
After Mettaton moved out of the way, Papyrus obeyed, stretching himself over the coach. It felt uncomfortably cool without his favorite sexy robot by his side, so when Mettaton straddled himself on top of him and gripped his hipbones, Papyrus sighed in relief, eager for what his partner is planning. The robot maneuvered his cone through the gap in the skeleton's pelvis, nudging his sacrum. Papyrus whimpered, digging his fingers into the cushions as Mettaton worked his way up to his spine. The robot drew back, teasing the sacrum again before returning to the vertebrae. He kept doing this, back and forth, back and forth, robbing Papyrus of breath as he resisted the urge to squirm.

“Is this good, darling?” Mettaton grinned, biting his lip to retain composure.  
“Yes...” Papyrus panted, wrapping his hand around his spine and the cone. “M-More, please! More...”  
  
Mettaton sucked air through his teeth as he pumped himself into the skeleton's hand. The robot's arms stretched and looped around Papyrus, holding him in place and fondling inside his ribcage. Papyrus gasped from the new and alluring sensations overwhelming his body, thrusting his hips to synchronize with his partner's movements. His right eye scorched with a neon blue flame, burning brighter the longer he writhed in bliss. The tip of Mettaton's cone lit the ribcage from below, casting beams of light from bone to bone like glittering crystals. But it wasn't all that lit up...  
  
“Oh my~” Mettaton murmured, slowing his pace. “What have we here?” Beating in the right side of his ribcage glowed Papyrus' soul; emerging as a result of the skeleton's magic, the azure heart hovered past his bones as it greeted the tips of Mettaton's fingers. Papyrus threw his head back, crying out from the way the robot touched him with such care and reverence. Cradling the skeleton's soul like the Holy Grail, the robot used his free hand to unbuckle his belt and release his own heart. “I... do believe... I have a friend for you...”  
  
Mettaton wasted no time mashing their souls together, pink and blue swirling together like cool rushing water. The robot screamed, near collapsing over his partner's body, and he would've fallen off if he hadn't tethered himself to Papyrus. Papyrus steadied themselves the best he could, one hand still around the spine and cone and the other clinging in desperation to his partner's shoulder-blade. He shuddered as Mettaton pounded into him again and again, all while clutching their souls and massaging them to circulate the ecstasy in their systems. As Papyrus wailed and matched his every thrust, the robot's voice shattered, and his cries glitched together in a drunken cacophony. The souls throbbed and dripped and suddenly it got to be too much. The skeleton's body went limp and his arms fell by their sides. A heavy tingly sensation permeated his bones, so strong that he couldn't move. By the time he came to, the magic in his eye-socket had smoldered away. Mettaton drooped over Papyrus's body, using his clavicle as a pillow.

“D-D-D-Darling, th-th-that was sensation-n-n-nal!” Mettaton hadn't recovered yet, and it would take some time before his voice-box adjusted to normal.  
“I... the Great Papyrus... declare this play-date—and our first time—a great sex-cess! Nyeh heh heh...!” Papyrus beamed, pulling his favorite celebrity into a warm hug. In a moment's pause, however, the skeleton frowned. “Wait a minute... Why am I making puns at a time like this?” Could he never truly escape his brother's terrible jokes? “Auuuuggh! Ignore what I just said! I change my mind! This is the WORST night!”  
  
Regardless whether the pun was accidental or not, Mettaton giggled, snuggling against his favorite skeleton. 

"It certainly w-w-won't be a ni-ni-night I'll forget anytime soon, d-darling." The robot smooched Papyrus' cheek.  
"Me neither, Mettaton..." Papyrus smiled sheepishly, stroking Mettaton's hair. "I'm glad we did this... I'd been so afraid something could go wrong, but we made it through together! Just the way it should be."  
"Yes..." Neither robot nor skeleton had the energy to move, so they just laid together on the coach, warmed by the glow of Mettaton's cone. Lucky underwear or not, they had all the time in the world, and there would be plenty of opportunity to try something like this again. But for now, they rest easy.


End file.
